WO2007118978A1

WO2007118978A1 - Total or partial trapezium bone replacement implant and method of manufacturing this implant

Info

Publication number: WO2007118978A1
Application number: PCT/FR2007/000548
Authority: WO
Inventors: Emmanuel Favreul; Jean-Jacques Martin
Original assignee: Small Bone Innovations International
Priority date: 2006-03-31
Filing date: 2007-03-30
Publication date: 2007-10-25
Also published as: FR2899095A1; FR2899095B1

Abstract

According to the invention, this implant (1) includes a body (2) and two inserts (3) made of a material resisting repeated friction against bone joint surfaces, particularly made of a metal material, the two inserts (3) being fixed to the body (2) so as to be facing said bone joint surfaces when the implant (1) is put into position.

Description

TOTAL OR PARTIAL REPLACEMENT IMPLANT OF A TRAPEZE BONE AND METHOD OF MANUFACTURING THE IMPLANT

The present invention relates to an implant for total or partial replacement of a trapezium bone.

French Patent Application No. 2 801 194 discloses an implant for total or partial replacement of a cuboidal bone, in particular trapezium, comprising a core of nonabsorbable rigid material, and a casing made of a non-resorbable fibrous material, with a structure porous. This implant has a form of revolution, rounded side wall and convex and truncated longitudinal ends, giving it the shape of a "small barrel".

By its curvature in two perpendicular planes, this implant makes it possible to perfectly restore the anatomical movement of the thumb and, thanks to its porous envelope, can be perfectly integrated with the surrounding tissues by growth of the cells in the pores of said envelope.

The implant according to this prior document, although giving overall satisfaction, however, has the important disadvantage of suffering wear in its areas cooperating with the joint surfaces of the bones concerned. Indeed, these articular surfaces are generally resected and therefore have relatively aggressive edges, which wear and / or notch the envelope of the implant. In addition to a defective operation of the joint, it results in a diffusion in the surrounding tissues of particles of the material forming said envelope, which generates an inflammation of these tissues and therefore joint pain.

The present invention aims to remedy this essential disadvantage.

Moreover, in general, the operation of the known implant can be improved.

EP 1 290 993, US 5 514 180, WO 01/70139 and EP 0 966 930 disclose vertebral implants unrelated to an implant for replacing a trapezium bone.

The implant that the invention relates to comprises:

- a body, and

two inserts made of material that is resistant to repeated friction against articular bone surfaces, in particular made of a metallic material, the two inserts being fixed to the body so as to face said articular bone surfaces when the implant is put in place. The articular bone surfaces therefore bear against these inserts during articular movements, which resist perfectly, given their constituent material, the friction and pressure that these surfaces exert on them. The aforementioned problem of implant wear and scattering of particles in the surrounding tissues is thus eliminated.

In addition, the shape of the inserts is independent of that of the body and can be adapted to that of the articular surfaces. Thus, the insert intended to cooperate with the first metacarpal may have a convex articular surface and the insert intended to cooperate with the scaphoid may have a concave articular surface.

The body advantageously has a porous structure in order to allow the implant to be held in position by growth of cells in the pores of this body. The implant may also include at least one suture connected to it, allowing its attachment to the surrounding tissue implantation site.

The body also advantageously has a slightly deformable structure, allowing its curvature and / or its axial compression.

This slight deformability allows an adaptation of the implant to the stresses transmitted by the bones between which this implant is put in place.

The implant may comprise guide means allowing guided mobility of one insert relative to the other. According to a preferred embodiment in this case, each of the inserts comprises a boss forming a hinge surface, one of the articulation surfaces being concave, in particular partially hemispherical, and the other surface being convex, these surfaces of articulation coming, when the implant is formed, in contact with one another. A multidirectional articulation of one insert relative to the other is thus obtained.

The body of the implant may in particular be constituted by a strip of porous material wound in a spiral so as to form a cylinder, the inserts being placed at the two axial ends of this cylinder. This porous material is preferably polyester, especially polyester terephthalate.

According to one possible embodiment of the invention, the body of the implant may in particular be constituted by a band of porous material wound in a spiral so as to form a cylinder comprising an axial cavity;

each insert comprises a boss pierced with a transverse hole intended to be engaged in this axial cavity, and

each insert is fixed to the body by means of sutures passing through at least once an area of the body wall, said transverse hole and an opposite zone of the body wall.

For carrying out the above insert, the method according to the invention comprises the steps of:

partially winding the strip of porous material so as to form a base cylinder;

engaging the bosses of the two inserts in the ends of the axial cavity formed by this base cylinder;

performing at least one suture traversing at least once a zone of the wall of the base cylinder, the transverse hole of the boss of a first insert, and an opposite zone of the wall of the base cylinder, then passing through an area of the wall of the base cylinder, the transverse hole of the boss of the second insert, and an opposite zone of the wall of the base cylinder;

- Wrap the rest of the porous material web around the base cylinder, thus covering said sutures, until integrally constituting the body of the implant.

Said sutures are thus perfectly protected against friction that may exert bones or surrounding tissues on the implant during joint movements.

The invention will be better understood, and other features and advantages thereof will become apparent, with reference to the appended diagrammatic drawing, showing, by way of non-limiting examples, two possible embodiments of the implant that it concerns. .

Figure 1 is a perspective view of three elements it comprises, according to a first embodiment; Figure 2 is a sectional view, after assembly; Figures 3 to 8 are sectional views in six successive steps of its manufacture; Figure 9 is a view after implantation; Figure 10 is a view similar to Figure 9, on an enlarged scale; Figure 11 is a perspective view of the three elements of the implant, according to the second embodiment; Figures 12 and 13 are side views of the implant, respectively in undeformed and deformed form, and Figures 14 and 15 are views respectively similar to Figures 12 and 13, in cross-section of the implant. .

For simplicity, elements or parts of elements that are found from one embodiment to another will be identified by the same reference numerals and will not be described again.

Figures 9 and 10 show an implant 1 total or partial replacement of the trapezoid bone, that is to say an implant intended to allow, after ablation of the trapezium, to restore the possibility of articulated movement of the first metacarpal 101 compared to the scaphoid 102.

As shown in FIGS. 1 and 2, the implant 1 comprises a body 2 and two inserts 3. It may also comprise one or more suture threads 4, connected to needles, for its attachment to the surrounding tissues its implantation zone. these wires 4 being engaged through the wall of the body 2.

The latter is constituted by a knitted and / or woven polyester terephthalate web, which is wound in a spiral so as to form an axial cavity cylinder, the inserts 3 being put in place at the two axial ends of this cylinder.

The inserts 3 are made of a metallic material, in particular stainless steel. Each of them has a circular portion 5, defining an articular surface 6, 7 on one side, and comprises a boss 8 projecting from the face of this circular portion 5 opposite to those defining said articular surface 6, 7.

The insert 3 intended to cooperate with the first metacarpal 101 has a convex articular surface 6 and the insert 3 intended to cooperate with the scaphoid 102 has a concave articular surface 7.

Each boss 8 is dimensioned such that it can be engaged in the axial cavity of the body 2, and is pierced with a transverse hole 9.

Figures 3 to 8 illustrate different successive steps of manufacture of the implant 1. The polyester terephthalate strip is first partially wound so as to form a base cylinder delimiting said axial cavity, and the bosses 8 of the two inserts 3 are engaged in this cavity, as shown in FIG. 3. A first suture thread 10 is then put in place as shown in FIG. 4, crossing twice a zone of the wall of the base cylinder, the transverse hole 9 of a first insert 3, and an opposite zone of the wall of the base cylinder, then crossing an area of the wall of the base cylinder, the transverse hole of the boss 9 of the second insert 3, and an opposite zone of the wall of the base cylinder. The ends of the wire 10 are then knotted (FIG. 5) and then fused, this wire 10 being made of a hot-melt material, in particular polyester (see FIG. 6).

A second suture 11 is then placed in the same manner, along an inverted path with respect to that shown in FIG. 4, that is to say starting from the face of the base cylinder situated on the right. of this figure (Figure 7).

The remainder of the polyester terephthalate web is then wrapped around the base roll, thus covering the threads 10, 11 and their sutures, until integrally forming the body 2 of the implant 1, as shown in FIG. 8, and the end of this band is fixed to the rest of the body 2 by a suture.

The implant 1 is placed in the space left free by ablation of the trapezium, and, where appropriate, is attached to the surrounding tissue by means of the son 4, so that the articular surfaces 6, 7 of the inserts 3 are facing the respective articular bone surfaces of the first metacarpal 101 and the scaphoid 102.

The articular bone surfaces therefore bear against the inserts 3 during articular movements, which resist perfectly, given their constituent material, the friction and pressure that these surfaces exert on them. Any problem of wear of the implant and diffusion of particles to the surrounding tissues is thus eliminated.

The articular surfaces 6, 7, respectively convex and concave, of the inserts 3 are adapted to the respective shapes of the articular surfaces of the first metacarpal 101 and the scaphoid 102.

The porous structure of the body 2 enables the implant 1 to be held in position by growth of cells in the pores of this body 2, and the latter is also slightly deformable to enable the implant 1 to be adapted to the stresses transmitted by the 101, 102, in particular a slight compression of the implant 1 in the direction of the approximation / removal of the inserts 3 from each other.

FIGS. 11 to 15 show an implant 1 of the same structure, that is to say comprising a body 2 and two inserts 3 with bosses 8 and holes 9. In this case, the boss 8 of one of the inserts 3 forms a concave articulation surface 15 and the boss 8 of the other insert 3 form a convex hinge surface, these surfaces being partially hemispherical.

As shown in FIGS. 12 to 15, these articulating surfaces 15, 16 come, when the implant 1 is formed, in contact with one another, thus forming a multidirectional articulation which allows the guided mobility of a insert 3 with respect to the other. The implant 1 can thus be deformed as shown in FIGS. 13 and 15, that is to say with curvature of the body 2.

The invention thus provides a total or partial replacement implant of a trapezium bone, which overcomes significant disadvantages of existing implants of the same indication.

It goes without saying that the invention is not limited to the embodiment described above by way of example but that it extends to all embodiments covered by the appended claims.

Claims

1 - Implant (1) for total or partial replacement of a trapezius bone, characterized in that it comprises:

a body (2), and

two inserts (3) of material that is resistant to repeated friction against articular bone surfaces, in particular of a metallic material, the two inserts (3) being fixed to the body (2) so that, when the implant (1) ) is put in place, one of the inserts (3) is located opposite the articular surface of the first metacarpal (101), and the other insert (3) is located opposite the articular surface of the scaphoid (102) .

2 - Implant (1) according to claim 1, characterized in that the insert (3) intended to cooperate with the first metacarpal (101) has a convex articular surface (6) and in that the insert (3) intended to cooperate with the scaphoid (102) has a concave articular surface (7).

3 - Implant (1) according to claim 1 or claim 2, characterized in that the body (2) has a porous structure.

4 - Implant (1) according to one of claims 1 to 3, characterized in that it comprises at least one suture (4) connected to it, allowing its attachment to the surrounding tissue implantation site.

5 - Implant (1) according to one of claims 1 to 4, characterized in that the body (2) has a slightly deformable structure, allowing its curvature and / or its axial compression.

6 - Implant (1) according to claim 5, characterized in that it comprises guide means for guided mobility of an insert (3) relative to the other.

7 - Implant (1) according to claim 6, characterized in that each of the inserts (3) comprises a boss (8) forming a hinge surface (15, 16), one of the articulation surfaces (15) being concave, in particular partially hemispherical, and the other surface (16) being convex, these articulation surfaces (15, 16) coming, when the implant (1) is formed, in contact with one another.

8 - Implant (1) according to one of claims 1 to 7, characterized in that the body (2) of the implant (1) is constituted by a strip of porous material wound in a spiral so as to form a cylinder, the inserts (3) being placed at the two axial ends of this cylinder. 9 - Implant (1) according to one of claims 1 to 8, characterized in that:

the body (2) consists of a porous material strip wound in a spiral so as to form a cylinder comprising an axial cavity;

each insert (3) comprises a boss (8) pierced with a transverse hole (9) intended to be engaged in this axial cavity, and

each insert (3) is fixed to the body (2) by means of sutures (10, 11) traversing at least once a zone of the wall of the body (2), said transverse hole (9) and an opposite zone of the body wall (2).

10 - Method for manufacturing an implant (1) according to claim 9, characterized in that it comprises the steps of:

partially winding the strip of porous material so as to form a base cylinder;

- engage the bosses (8) of the two inserts (3) in the ends of the axial cavity formed by the base cylinder;

- Making at least one suture (10, 11) traversing at least once an area of the wall of the base cylinder, the transverse hole (9) of the boss (8) of a first insert (3), and an opposite zone from the wall of the base cylinder, then through an area of the wall of the base cylinder, the transverse hole (9) of the boss (8) of the second insert (3), and an opposite zone of the wall of the base cylinder;

- Wrap the rest of the band of porous material around the base cylinder, thus covering said sutures (10, 11), until integrally the body (2) of the implant (1).